The invention concerns a passive restraining system for a motor vehicle, which has at least one airbag module allocated to a vehicle seat for lateral protection of the head and optionally the head-chest region of a person sitting in the vehicle seat. The airbag module has at least one gas generator and a gas sack into which the gas generator introduces gas suddenly upon a triggering signal. One proceeds from the assumption that the person is additionally secured with a customary safety belt.
Such a system is known from PCT publication WO-A-95/19899 as well as from U.S. Pat. No. 5,556,129. The first mentioned publication describes a restraining system in which the mentioned safety belt is anchored in the structure of the vehicle, thus, for example, in the B or C column. The latter publication, on the other hand, concerns the case where the safety belt is integrated into the vehicle seat.
Lateral impact protection has for some time increasingly occupied the interest of the branches of industry engaged in the manufacture of motor vehicles. There are already vehicles which serially have at their disposal so-called side airbags. Typical side airbag constellations are mentioned only as an example. Thus, for example, a system is known from European published patent application EP-A1 0 560 501 in which a separate airbag for the chest region and a further airbag for the head region are allocated to a vehicle seat. A combined head-chest airbag is already known from unpublished German patent application 195 29 829 of the present applicant. It is proposed therein in the event of an impact to inflate a gas sack which includes two chambers on the side of the seat to which the module is allocated. One of the chambers is here allocated to the head region and the other chamber to the chest region of the person sitting in the seat in question.
In the event of a lateral collision with another vehicle, the front part of the other vehicle in the accident typically first penetrates the lower door area, whereby the pelvic area of the affected vehicle occupant is thrust in the direction of the vehicle interior. Typically, the glass panes of the doors shatter and the side airbags are inflated. The head and chest region then make an evasive maneuver in the direction of the inflated head airbag or head-chest airbag. At this point there exists the danger that, due to the head striking the airbag, the head swings outward through the now glassless window opening. The head of the vehicle occupant hereby experiences a strong nodding movement owing to the lack of resistance, which can lead to injuries in the neck region, which can bring with them late sequelae such as migraine problems and others. The problems represented above occur, moreover, all the time in connection with open vehicles such as convertibles, which have no upper support structure available, or even with closed vehicles with opened side windows.